Dehydrated model food systems, fortified with retinyl acetate, ascorbic acid, riboflavin and a combination of all three vitamins, were equilibrated to aw's of 0.10, 0.24, 0.40, 0.50 and 0.65 and stored at 10, 20, 30 and 37C in containers permeable and unpermeable to oxygen. Under all storage conditions retinyl acetate and ascorbic acid (total and reduced ascorbic acid) degraded according to first-order kinetics. Rate constants for ascorbic acid were a function of aw and storage temperature for model systems containing ascorbic acid or vitamins A, B2 and C in combination. Neither aw nor storage temperature greatly affected retinyl acetate alone or in combination of vitamin B2 and C at 20 or 30C. At 10C the stability or retinyl acetate was greatly increased when ascorbic acid was present. The presence of additional oxygen in the samples stored in paperboard boxes significantly increased the rate of ascorbic acid and retinyl acetate degradation. Riboflavin was shown to be stable under all storage conditions except 37C and high aw. In these cases, half-lives were decreased by 50 to 75 percent. Rate constants for riboflavin destruction in the presence of oxygen were first order and similar to the high temperature and aw sample. BIBLIOGRAPHIC REFERENCES: Kirk, J. R. 1974. Automated method for the analysis of riboflavin in milk, with application to other selected foods. J. A.O.A.C. 57:1085-1088.